Protection from direct human impacts can safeguard marine life, yet ocean warming crosses marine protected area boundaries. Here, we test whether protection offers resilience to marine heatwaves from local to network scales. We examine 71,269 timeseries of population abundances for 2269 reef fish species surveyed in 357 protected versus 747 open sites worldwide. We quantify the stability of reef fish abundance from populations to metacommunities, considering responses of species and functional diversity including thermal affinity of different trophic groups. Overall, protection mitigates adverse effects of marine heatwaves on fish abundance, community stability, asynchronous fluctuations and functional richness. We find that local stability is positively related to distance from centers of high human density only in protected areas. We provide evidence that networks of protected areas have persistent reef fish communities in warming oceans by maintaining large populations and promoting stability at different levels of biological organization.

The analysis of spatial variability in distribution and abundance of echinoderms may help in identifying the range of processes that can explain the observed patterns of this important component of benthic communities. The distribution and abundance of the echinoderm assemblage inhabiting the shallow rocky reefs at the Cabo Verde archipelago (where few studies other than descriptive ones have been performed until now) was quantified at three spatial scales (among islands, between locations within islands, and among replicates), at two depth strata, and related to fine-scale variation of habitat structure. Total echinoderm abundance and the abundance of the sea urchins Diadema antillarum and Eucidaris tribuloides, and the holothurian Euapta lappa were heterogeneous at the largest considered scale. Most species and habitat descriptors exhibited spatial variability at finer scales. There were significant relationships between habitat architecture and depth and both assemblage parameters and species abundances. Although the effects of habitat structure were species-specific, the probability of occurrence of Asteroidea, Ophiuroidea and Holothuroidea species was higher in heterogeneous habitats. Meanwhile Echinoidea and Holothuroidea species showed higher correlations to complex habitats. The observed spatial patterns are inferred to reflect behavioural responses to fine-scale microhabitat complexity, as well as broad-scale oceanic variables and recruitment dynamics.